Today I was meddling around with the network configurations as I could not connect to a wired network, and with something I did, when I restarted I was keeping on getting the message "Waiting for network configuration at boot up in ubuntu" and then wait upto 60 seconds, and start up without any network manager settings.
Because of this I could not connect to a network, and the network manager was literally stalled.
After looking at my previous steps, hitting the history command
it shows that I was meddling with the resolve.conf file. But when I looked at the file, it showed that no DNS nameservers were defined in the file. The file was EMPTY.... PANIC!!!!
So then I tried setting the nameserver in the /etc/resolve.conf file, however it was getting replaced.
The solution was,
1) go to /etc/resolveconf/resolv.conf.d/
# cd /etc/resolveconf/resolv.conf.d/
2) Open the base file n super user mode
# sudo vim base
3) add the nameserver details
e.g : nameserver 127.0.1.1
4) Save file, and restart.
This should fix the issue.